方法一

#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
int main(){
    string a;
    int b;
    cin >> a >> b;
    int remand = 0;
    string res = "";
    int tmp;
    for(int i = 0; i < a.size(); i ++ ){
        tmp = remand * 10 + (a[i] - '0');
        res += tmp / b + '0';
        remand = tmp % b;
    }
    int flag = 1;
    for(int i = 0; i < res.size(); i ++ ){
        if(flag){
            if(res[i] != '0'){
                flag = 0;
                cout << res[i];
            }
        }else   cout << res[i];
    }
    if(flag == 1)   cout << "0" << endl << a << endl;
    else    cout << endl << remand << endl;
    return 0;
}

方法二

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
vector<int> div(vector<int> &A, int b, int &r){
    vector<int> C;
    for(int i = 0; i < A.size(); i ++ ){
        r = r * 10 + A[i];
        C.push_back(r / b);
        r %= b;
    }
    reverse(C.begin(), C.end());
    while(C.size() > 1 && C.back() == 0)    C.pop_back();
    return C;
}
int main(){
    string a;
    int b;  cin >> a >> b;
    vector<int> A;
    for(int i = 0; i < a.size(); i ++ ) A.push_back(a[i] - '0');
    int r = 0;
    vector<int> C = div(A, b, r);
    for(int i = C.size() - 1; i >= 0; i -- ) cout << C[i];
    cout << endl << r << endl;
    return 0;
}